Y. Nikitin, F. Guinea and L. Martin Moreno, Appl. Phys. Lett., 2012, 101 ... G.
Pirruccio, G. Lozano, L. Martin Moreno and J. Gomez Rivas, submitted. V. G.
Kravets ...
Coherent and broadband enhanced optical absorption in graphene Giuseppe Pirruccio
[email protected]
www.amolf.nl/surfacephotonics
Acknowledgments Funding: Luis Martin Moreno Gabriel Lozano Jaime Gomez Rivas
Outline Motivation and introduction Coherent absorption Measurements and modeling Optimization Conclusions
Motivation Graphene based photodectors: Absorbs from UV to THz High carrier mobility
Problem: the low absolute value of the absorption of graphene (2.3% of the incident light) limits the photocurrent efficiency F. Xia, T. Mueller, Yu. Li, A. Valdes-Garcia and P. Avouris, Nat. Nanotech. 2009, 4, 839. F. Bonaccorso, Z. Sun, T. Hasan and A. C. Ferrari, Nat. Photon., 2010, 4, 611.
Enhanced photodetection
Not ideal for broadband absorption
Microcavity realized through Bragg mirrors (optimized for narrow wavelength - angular window) M. Furchi, et al., Nano Lett., 2012, 12, 2773 M. Engel, M. Steiner, A. Lombardo, A. C. Ferrari, H. v. Lohneysen, P. Avouris and R. Krupke, Nat. Commun., 2012, 3, 906.
Hybrid devices
G. Konstantatos, M. Badioli, L. Gaudreau, , J. Osmond, M. Bernechea, F. P. Garcia de Arquer, F. Gatti and F. H. L. Koppens, Nat. Nanotech., 2012, 7, 363. Z. Fang, Y. Wang, Z. Liu, A. Schlather, P. M. Ajayan, F. H. L. Koppens, P. Nordlander and N. J. Halas, ACS Nano, 2012, 6, 10222
Plasmonics to enhance absorption
S. Thongrattanasiri, F. H. L. Koppens and J. Garcia de Abajo, Phys. Rev. Lett., 2012, 108, 047401. Y. Nikitin, F. Guinea and L. Martin Moreno, Appl. Phys. Lett., 2012, 101, 151119.
Outline Motivation and introduction Coherent absorption Measurements and modeling Optimization Conclusions
Scattering problem Perfect energy transfer between incoming channels (optical modes) and the structure.
Building a destructive interference pattern in the far-field will cause the light to be trapped in the structure. The material losses will eventually dissipate the energy.
(ωinc, k inc) Weakly absorbing material
Coherent Perfect Absorption 2 channels CPA
Weakly absorbing material
W. Wan, Y. Chong, L.Ge, H. Noh, A. Douglas Stone and H. Cao, Science, 2011, 331, 889.
From 2 to 1 channel 1 channel CPA (single port reflector) Perfect mirror Absorbing cavity
Mirror Absorbing cavity
Total internal reflection Graphene (multi)layer
W. Wan, Y. Chong, L. Ge, H. Noh, A. Douglas Stone and H. Cao, Science, 2011, 331, 889.
Outline Motivation and introduction Coherent absorption Measurements and modeling Optimization Conclusions
Graphene characterization 10 layers
10 layers 5 layers 5 layers 1 layer
1 layer
CVD deposition of graphene on copper foils. PMMA transfer onto silica substrates (turbostratic deposition)
G. Pirruccio, G. Lozano, L. Martin Moreno and J. Gomez Rivas, submitted. V. G. Kravets, A.N. Grigorenko, R. R. Nair, P. Blake, S. Anissimova, K. S. Novoselov and A.K. Geim, Phys. Rev. B, 2010, 81, 155413
Sample
dsilica = 590 – 1300 nm
Magnetron-sputtering in steps (low temperature on graphene)
θ c , 2 < θ c ,1
Absorptance measurements Absorptance (5 layers)
When θ*
